114 Description of Mr. Perkins’ New Steam-Engine. 
steam of constant elasticity is supplied to produce the 
power. 
‘Some philosophers are of opinion, that the heat of the 
portion of water which escapes, is of itself sufficient to 
maintain the steam at that high degree of heat and elasti- 
city with which it reaches the piston, and, consequently, 
that this engine is nothing more than a High Pressure En» 
gine. Other persons, however, have supposed, and we 
confess we are among that number, that the portion ‘of wa- 
ter which escapes, must necessarily carry off ‘a quantity of 
heat from the adjoining stratum (the temperature of which 
may be thus reduced below the freezing point.) But it is 
more likely, that in virtue of some new law of the trans- 
mission of heat under the combined conditions of elevated 
temperature and high pressure, while the water, also, is for- 
ced to remain in contact with the red hot generator, the 
whole water in the boiler may be laid under requisition te 
furnish the discharged fluid with its necessary supply of ca- 
loric. 
It is almost unnecessary to state, that the motion of the 
by the difference , 
the reUbdeflier, acts with only 70, the dherenoal or 230Ib.. 
being the true tated e ined. 
which is w vig the engine. ‘This pump draws the wa- 
ter by the pipe 6, 6, 6, from the condenser STXYV, and re- 
turns it by the pipe 4, 4, 4; that is to say, when the handle 
M is drawn up, the water ‘rushes into the menpetys of the 
forcing pump, through a valve in the pipe 6, 6, 6, opening 
into that cylinder: This valve, of course, instantly closes 
when the downward stroke of the pump is made, ‘and the 
